One of the largest problems involved with deployment of conventional air dropped sonobuoys is the release of apparatus carried in a sonobuoy package, once the sonobuoy has impacted the ocean and is floating on the surface of the ocean. It will be appreciated that sonobuoys depend upon submerged sensing apparatus and that this sensing apparatus must be released for the proper operation of the sonobuoy. While various sonobuoy end cap release mechanisms have been utilized in the past, one of the major problems with these mechanisms is the reliability of the release. Should the end cap not release, the sonobuoy is rendered inoperative. One of the factors affecting the reliability of the release of the end cap is the entry angle of the sonobuoy as it impacts the ocean surface. Various stabilizing apparatus such as parachutes and rotochutes have been utilized to maintain a vertical entry angle of the sonobuoy. However, in each of these configurations the sonobuoy swings during descent and may therefore enter the ocean at angles other than along the local vertical. Should this occur, those release mechanisms depending on impact pressure for the release of the end cap often fail.
One type prior art bottom release mechanism is illustrated in U.S. Pat. No. 3,275,976 issued to E. W. Farmer Sept. 27, 1966. In this patent a rigid detent member is moved in an upward direction upon impact of the sonobuoy thereby permitting the release of a spring loaded pin and the subsequent release of the end cap. While this device works satisfactorily for most entry angles there is a possibility of the canting of the rigid detent against the side wall of the chamber in which it is located when the sonobuoy enters the ocean at a fairly oblique angle. When there is sufficient stabilization time, as in high-altitude sonobuoy drops, the Farmer device works quite adequately. However, in low altitude drops there may be insufficient time for the stabilization of the sonobuoy and the sonobuoy may enter the ocean surface at entry angles exceeding plus or minus 45.degree. of the local vertical. In this situation it is possible for the pressure to be applied to the nondeformable rigid detent in such a way as to cause failure of this member.
The subject invention improves on the Farmer release mechanism by providing a deformable detent member for the release of the spring loaded pin. In one embodiment an outwardly-bowed or convex leaf spring member is provided with a slot or aperture which coacts with an annular flange or boss on the spring loaded pin. In normal operation the boss is located in the slot and the slot locks the pin against the spring loading so as to maintain the end cap securely fastened to the bottom of the sonobuoy package. Upon impact the flexible leaf spring is depressed at which time the slot comes out of engagement with the boss on the spring loaded pin and the spring loaded pin is then released, thereby allowing the end cap to fall free from the sonobuoy package. The leaf spring is anchored at only one end, with the other end of the leaf spring being free to slide when the leaf spring is depressed by water impact. It is a finding of the subject invention that this configuration permits reliable release of the end cap regardless of the angle of entry of the sonobuoy assuming the sonobuoy does not land on its side or bottom up. In another embodiment the spring loaded pin is maintained in position by a frangible member which is deformed under impact and completely breaks up or disintegrates. The frangible member is so designed and positioned such that it locks the spring loaded pin against the spring loading until such time as the frangible member is broken by water impact. The frangible detent may, of course, take on any of a variety of forms and all such forms are within the scope of the present invention.
It will be appreciated that what has been provided is a releaseable end cap carrying a deformable detent member which is deformed upon water impact to release a spring loaded pin also carried by the end cap which then translates out of a locking engagement with the sonobuoy package to permit release of the end cap. By "deformable" is meant that the detent member is either flexed for displacement away from the spring loaded pin or is in fact destroyed thereby releasing the spring loaded pin.
It is therefore an object of this invention to provide an improved bottom release mechanism for air dropped sonobuoys and the like;
It is another object of this invention to provide a deformable detent member for use with a spring loaded locking mechanism for reliable release of end caps provided for air dropped apparatus;
It is a still further object of this invention to provide a deformable member in the form of either a deformable leaf spring or a frangible member which maintains a spring loaded locking member in locking engagement until such time as air dropped apparatus carrying this member impacts the surface of the ocean at which time the deformable member releases the spring loaded locking member.